1. Field of the Invention
The invention concerns a deformable mirror having an at least quasi-continuously deformable optical effective surface, and a plurality of electrically actuable adjusting members which engage behind the surface and which are arranged in a housing.
2. Discussion of the Prior Art
A mirror of the general kind set forth is known from DE 35 02 025. Formed on the rear side of the mirror are projections which permit punctiform engagement for adjusting members. Those projections are permanently connected to the adjusting members by way of a sleeve which transmits a variation in the length of the adjusting member to the mirror plate by pulling or pushing. The mirror plate itself is held by way of a peripherally extending rubber seal in an end flange of a hollow cylinder. The hollow cylinder at its rear carries a support for the adjusting members.
That design configuration has basically proven its worth for compensating for phase differences of an incident wave front. However, the elastic fixing of the mirror plate to the housing has proven to be disadvantageous in a practical situation, for the adjustment requirements. Thus, as the adjusting members are to be clamped between the mirror plate and the support, the arrangement can involve local deformation of the mirror plate which in that case is partially displaced out of the zero or neutral position or the working point. As a consequence of this, that structure then lacks a flat mirror surface as a reference for corrections.
In consideration of those factors the technical object of the present invention is therefore that of providing a deformable mirror of the general kind set forth, the mirror plate of which is so mounted that it can be set with its predetermined planarity to a working point, around which local actuating control actions are then implemented.
In accordance with the invention that object is attained in that the mirror plate is supported in a contactless manner to an open end face of the housing along its edge by a group of at least three adjusting members. In accordance therewith the deformable mirror designed in accordance with the invention comprises a deformable mirror plate in front of a housing, wherein the optically effective surface of the mirror plate faces away from the housing. At the housing side, behind the optically effective surface, a group of electrically-actuable adjusting members engages the rear side along the edge of the mirror plate and holds same in contact-free relationship with respect to the housing in front of the open end face thereof. For that purpose, at least three adjusting members which are not disposed on a line are arranged along the edge of the mirror plate in space by means of electrical actuation. Besides those adjusting members along the edge, which function as a holder and for working point adjustment, a group of adjusting members is arranged in distributed fashion over the rear side of the mirror plate, which adjusting members can implement deformation of the mirror plate at each respective location, namely around the stationary length presetting of the adjusting member outwardly or inwardly.
A coupling portion in front of each adjusting member is permanently fixedly connected, for example by adhesive means, to the adjusting member and to its end remote from the adjusting member, at the rear side of the mirror. Preferably the adjusting members of piezo-ceramic material in ring form are stacked to form columns. In order to achieve continuous deformation of the mirror plate, the front coupling portions each have a constriction which acts as a desired-flexion location and thus prevents a blatant stepped transitional configuration of the mirror plate between the deflections of adjacent adjusting members.
In addition also permanently mounted to each adjusting member at the rearward part thereof is a holding portion provided with a female screwthread. By means of a screw, it is possible to fix a respective adjusting member to a base component which represents the rearward closure of the housing, in front of the front end of which the mirror plate is disposed. Besides holding holes for the screws, that base component has an equal number of through holes for actuating cables leading to the adjusting members. For fixing each adjusting member on the base component, referred to in the optical construction art as the tube, a screw engages with its shank through a holding hole and into the female screwthread of the holding portion so that the base component is axially clamped between the rearward screw head and the holding portion which is disposed in front of same. In that way the adjusting member is held in front of the base component.